1. Field of the Invention
This invention relates to an ink jet recording head, and more particularly to an ink jet recording head for recording by ejecting a liquid and depositing the resulting flying droplets onto a material to be recorded.
2. Description of the Prior Art
An ink jet recording apparatus for generating ink droplets and depositing the droplets onto a material to be recorded such as paper, etc., thereby carrying out recording has been regarded as important because the recording apparatus generates only negligibly small noise during the recording and can ensure high speed recording on the ordinary paper without any special treatment such as fixation, etc. Recently various types of the apparatuses have been under active study.
One example of a recording head applicable to such an ink jet recording apparatus is shown in FIGS. 1A and 1B, where numeral 1 is a recording head with a discharge energy generating element (not shown), and 2 is a drive board that feeds a discharge signal to the recording head 1. The recording head 1 and the drive board 2 are both provided on a support member 3. To prevent the electrical connection therebetween from any damage due to contamination by exuded ink, etc., a gap groove 4 is provided between the recording head 1 and the drive board 2 to maintain the specific clearance. An insulating adhesive 5 is inserted in the gap groove 4, and an adhesive 7 is inserted in an adhesive opening 6 provided in the support member 3 to fix the recording head 1 to the support member 3.
Numeral 8 denotes signal wires that feed a singnal to the recording head 1 from the drive board 2 and are connected onto bonding pads (not shown in the drawings) provided on both sides across the gap groove 4. The recording head 1 and the drive board 2 are inserted into and supported with a front support plate 9 through an elastic bushing 10, and a capping 12 made of an elastomer is detachably provided on the ink discharge side of the plate 9 to prevent the ink from drying when the recording head 1 is not used.
Ink feed pipes 13 are provided on the recording head 1 and can supply the ink through a recovery pump (a pump used for recoverying ejection of ink when ejection of ink is unintentionally stopped) (not shown in the drawings) during the recovery operation to stabilize printing. That is, the ink can be ejected from a nozzle 1A by forced supply of the ink.
However, when the ink is ejected from the nozzle 1A by the recovery operation in such a conventional ink jet recording head as above, the ejected liquid ink permeates the clearance at the joint surface between the recording head 1 and the support member 3 by the trickling down along the front surface, and the permeating ink exudes onto the side surfaces from the joint surface, while further proceeding around the adhesive 5 in the gap groove 4 to wet the electric connection portion between recording head 1 and drive board 2 and the upper side of drive board 2, generating a short circuit on the drive board.
Furthermore, when the clearance of gap groove 4 is small, it will be not only difficult to apply thereto the adhesive 5 so as to prevent the permeation of the ink, but also the adhesive is liable to deposit on the pads on the side of recording head 1 and that of drive board 2, causing trouble in the connection of the signal wires 8. This leads to waste, whereas when the clearance of gap groove 4 is too large, and when the recording head 1 is higher in density, the density of the signal wires 8 will be also higher and consequently short circuits will be more likely to occur between the adjacent wires 8.
That is, the recording head of such a conventional kind has sometimes a problem not only in the reliability as described above, but also in the decrease in the productivity.